1. Technical Field
The present disclosure relates to an electronic apparatus and an image forming apparatus, and more particularly to a technique of detecting an amount of movement of an object to be rotated by a driving force of a driving motor.
2. Related Art
In electronic apparatuses such as an image forming apparatus that employs an electrophotography method, a developing unit supplies a toner to a static latent image formed on the surface of a photoconductor drum or an intermediate transfer belt, to thereby develop the image. The toner is stored in a toner container, which is driven by a driving motor when the toner density in the developing unit drops, so that the toner in the toner container is stirred with a stirring paddle and supplied to the developing unit with a conveyor screw. Therefore, the amount of the toner supplied to the developing unit can be calculated from the amount of movement of the toner container (conveyor screw). When thus calculating the amount of the toner supplied to the developing unit from the amount of movement of the toner container, the torque of the driving motor has to be taken into account because the amount of movement varies depending on the torque.
Now, in some image forming apparatuses (general apparatus A) the CPU is configured to decide whether the current and torque of the driving motor have largely fluctuated within a predetermined period of time. In the case where the torque has largely fluctuated, i.e., in the case where the toner has been unexpectedly supplied to the developing unit, the CPU stops the supply of the toner from the toner container to the developing unit for a predetermined period of time, and detects the toner density in the developing unit after the predetermined period of time has elapsed and then resumes the regular supply of the toner to thereby properly form the images.
In some other image forming apparatuses (general apparatus B), a rotation speed detector and a current controller are employed when driving a DC servo motor, to calculate the driving torque on the basis of the correlation between the number of rotations and the supply current.